Abaixo está uma instrução que descreve uma tarefa de geração de SQL, combinada com uma entrada que fornece mais contexto sobre os esquemas de tabela disponíveis. Escreva o código SQL que responda adequadamente à solicitação
 ###Instrução: Quantas semanas de semifinal existem para atos de Pittsburgh, Pensilvânia?
 ###Tabelas: CREATE TABLE general_standings (general_standings_id AUTO_INCREMENT PRIMARY KEY, Cyclist VARCHAR, Nation VARCHAR, Team VARCHAR, Time VARCHAR, UCI Points INT) CREATE TABLE donald_campbell's_unlimited_world_water_speed_records (donald_campbell's_unlimited_world_water_speed_records_id AUTO_INCREMENT PRIMARY KEY, Speed VARCHAR, Craft VARCHAR, Pilot VARCHAR, Location VARCHAR, Date VARCHAR) CREATE TABLE conference_winners_and_tournaments (conference_winners_and_tournaments_id AUTO_INCREMENT PRIMARY KEY, Conference VARCHAR, Regular Season Winner VARCHAR, Conference Player of the Year VARCHAR, Conference Tournament VARCHAR, Tournament Venue (City) VARCHAR, Tournament Winner VARCHAR) CREATE TABLE round_chart (round_chart_id AUTO_INCREMENT PRIMARY KEY, Name/Name of Act VARCHAR, Age(s) VARCHAR, Genre VARCHAR, Act VARCHAR, Hometown VARCHAR, Qtr. Final (Week) INT, Semi Final (Week) VARCHAR, Position Reached VARCHAR) CREATE TABLE first_round_proper (first_round_proper_id AUTO_INCREMENT PRIMARY KEY, Tie no VARCHAR, Home team VARCHAR, Score VARCHAR, Away team VARCHAR, Attendance VARCHAR)  
SELECT COUNT Semi Final (Week) FROM round_chart WHERE Hometown = Pittsburgh, Pennsylvania